Electrical interconnection device

ABSTRACT

A CERAMIC PLATE HAS, THROUGH ITS NARROWEST DIMENSION, AN APERTURE OF GENERALLY CIRCULAR CROSS SECTION. A SILVER MASS IS MELT-BONDED TO THE WALL OF THE APERTURE. THE VOLUME OF SAID MASS IS SUCH THAT IT RANGES FROM CONSIDERABLY MOVE TO SLIGHTLY LESS THAN THE VOLUME OF SAID APERTURE.

United States Patent [72] inventor Vernon V. Hukee Nashua, N11. [21] Appl. No, 803,224 [22] Filed Feb. 28, 1969 [45] Patented June 28, 1971 [73] Assignee Sprague Electric Company North Adams, Mass.

[54] ELECTRICAL INTERCONNECTION DEVICE 6 Claims, 4 Drawing Figs.

[52] 0.8.01. 200/11, 200/166, 317/101 [51] Int. Cl 01h 1/00, H05k H04 [50] Field oiSearch 317/101; 200/1 1, 166 (E), 166 (B8), 166 (C) [.56] References Cited UNITED STATES PATENTS 3,514,556 5/1970 La France 200/43 Primary Examiner- Robert S. Macon Assistant Examiner-J. R. Scott Attorneys-Connolly and Hutz, Vincent H. Sweeney, James Paul OSullivan and David R. Thornton ABSTRACT: A ceramic plate has, through its narrowest dimension, an aperture of generally circular cross section. A silver mass is melt-bonded to the wall of the aperture. The volume of said mass is such that it ranges from considerably more slightly less than the volume of said aperture.

1 ELECTRICAL INTERCONNECTION DEVICE BACKGROUND OF THE INVENTION The present invention relates to an electrical interconnection device more particularly to a device for making electrical connection from one side ofa planar surface to another side of a planar surface.

Common prior art techniques for making electrical connection from one planar surface to another generally fall into two classes: (I) the use of rivets, eyelets, slips, wires extending through apertures, etc.; and (2) the use of conductive coatings extending through holes or around the edge of the substrate. Techniques falling into the first group are generally expensive, difficult and somewhat bulky. Techniques falling into the second group are difficult to apply in a manner which insures reliability.

An object of this invention is to provide an electrical interconnection means which overcomes the above-indicated disadvantages.

Another object of the present invention is to present electrical interconnection means which is economical and ideally suited for automated assembly methods.

A further object of the invention is to present a structure affording the option of electrical connection from either side of a substrate.

Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawing wherein similar reference characters refer to similar parts and in which:

FIG. 1 is a side view in section of an electrical interconnection means of the present invention;

FIG. 2 is a plan view of a ceramic blank with a plurality of melt-bonded silver masses in a plurality of apertures used for forming individual electrical mounting means;

FIG. 3 is a perspective view of an electrical interconnection means of the present invention having various components mounted thereon; and

FIG. 4 is a side view of an electrical contact device employing the electrical interconnection means of the present invention.

SUMMARY OF THE INVENTION In general this invention involves a combination, a ceramic plate having across its narrowest dimension at least one curved wall and a silver mass melt-bonded to said curved wall. The volume of said mass being such that it ranges from considerably more to slightly less than that which would completely fill the volume defined by said curved wall. In a limited embodiment of the present invention, the curved wall defines at least one aperture of generally circular cross section in said plate. In another embodiment of the invention the curved wall defines at least one trough across an edge of said plate, the cross section of said trough being part of a circle. Another limitedversion of the combination of the present invention has at least one aperture of generally circular cross section and at least one trough across an edge thereof, the cross section of said trough being part of a circle.

In a further embodiment of the present invention a plurality of apertures are spaced in a circular pattern in the ceramic plate. Each aperture has a silver mass which extends beyond said aperture above the planar surface of the plate. This arrangement forms a circular pattern of raised silver contact areas. A rotatable nonconducting rotor is positioned adjacent the silver contact areas, the rotor having at least one conducting area which can be brought into electrical contact with a silver contact area on rotation of said rotor.

In another aspect ofthe present invention one or more electrical components are in electrical communication with one or more of the silver masses so as to accommodate electrical communication to said components from either the edge or the opposite surface of said ceramic plate.

In a further embodiment of the present invention one or more electrical components are positioned on a ceramic substrate in electrical communication with one or more of the silver masses and an insulating layer covers at least part of the component side of said substrate, including the exposed portion of said silver masses, the electrical components and all of the electrical communication region between said masses and said components. In such an arrangement the silver masses extend above the planar surface of said substrate a distance which permits lap-removal of some of said insulating material from one or more of said silver masses without uncovering said components.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a section of a ceramic plate 10 having therein a silver mass 12 positioned in an orifice 14. Silver mass 12 is melt-bonded, as at 16, to the wall of said orifice.

FIG. 2 shows a ceramic plate 18 having a plurality of silver filled orifices 20. Lines 22 and 24 indicate the paths along which a cutting device will follow in order to segment the ceramic plate. 7

FIG. 3 shows a microcircuit assembly 26 such as would be obtained from area 26 of FIG. 2 and which has thereon a plurality of components 28, 30 and 32 in electrical communication with silver masses 20 mainly by way ofleads 50.

FIG. 3 also shows, in spaced relationship for purposes of clarity, an insulating film 48 deposited on assembly 26 and covering the electrical components, the exposed portion of said silver masses and the leads 50. In this embodiment, silver masses 20 extend from the surface of the substrate a distance greater than the thickness of the components and the contours 52 of silver masses 20 are plainly revealed in film 48.

FIG. 4 shows a switch assembly 34 having a ceramic plate 36 which contains a plurality of silver masses 38 melt-bonded into orifices in said ceramic plate. Leads 46 are in communication with masses 38. An insulating rotor 40 has electrically conducting areas 42 located thereon. The rotor is located adjacent to said silver masses 38 so that on rotation of said rotor via knob 44, one or more of said conducting areas can be brought into contact with one or more of said silver masses.

DETAILED DESCRIPTION OF THE INVENTION Example I An alumina plate approximately one thirty-second of an inch thick has a plurality of circular apertures 30 mils in diameter formed therein. Into each of these apertures is seated a spherical silver mass approximately 31 mils in diameter. The plate and the silver are then subjected to a temperature (e.g. l900 F.) which is considerably in excess of the melting point of silver. The silver spheres become molten and flow substantially completely within the aperture and on cooling the silver mass becomes melt-bonded to the wall of the aperture. Thereafter, a microcircuit of predetermined design is positioned on one planar surface of the alumina and electrical contact is made to various components of the circuit in such a way that the silver masses accommodate electrical communication to said components from the opposite surface of the alumina plate.

Example ll Another ceramic plate, approximately one thirty-second of an inch in diameter, has a plurality of apertures, approximately 60 mils in diameter, formed therein. Thereafter, in these apertures are seated spherical silver masses having a diameter of 62 mils. The ceramic plate is subjected to a temperature of approximately l900 F. The silver masses flow substantially completely into the orifices. The ceramic plate is then cut into a plurality of rectangular plates so that each plate has silver masses that are of half round configuration, some are of quarter round configuration and some are of full round configuration. A plate of this type is shown in FIG. 3. Individual microcomponents are mounted on one planar surface of a soformed ceramic rectangle and placed in electrical communication with selected silver masses via a commercial silver paint. This affords both edge contact to the components and also affords communication to said components from the opposite planar surface of the ceramic plate. in a modification of the arrangement described in Example ii, the size of the spherical silver mass is such that after firing the silver in place in the orifices, part of the mass will extend above the planar surface of the ceramic plate a distance greater than the thickness of the circuit or components mounted thereon. With the circuit or components in place on the ceramic plate and in electrical communication with the silver masses, an insulating film of glass, silica or the like is coated over the silver, the circuit or components and their interconnecting leads. This film should ideally reveal the contour of the silver masses protruding from the orifices or troughs in the plate.

This modification provides the option of either lap-removing, by suitable means, e.g. abrasive means, the insulation covering one or more of the silver masses or leaving the insulation intact and making further electrical connection from the opposite side of the ceramic plate. It should also be understood that this arrangement will permit selective electrical connection from both sides of the unit.

The switch or contact means illustrated in FIG. 4 is conveniently made from a ceramic plate of about one thirtysecond of an inch thick. A series of holes each about 40 mils in diameter is arranged in a circle of about one-half inch in diameter. Silver spheres having a diameter of about 50 mils are seated in the orifices. The ceramic plate and silver spheres are subjected to a temperature of about 1900 F. to flow the silver into the orifices. A mound of silver protrudes from each orifice on one side of the ceramic plate. On the opposite side of the plate, the silver is nearly even with the planar surface. An insulating rotor of organic or inorganic material is provided on one side with one or more electrically conducting lands and on the other a knob to facilitate rotation of the rotor. The rotor is rotatably mounted on the ceramic plate so that the electrically conducting lands can be brought into contact with one or more protruding mounds of silver. The switch is then ready for connection with any suitable device or circuit from the opposite side of the ceramic plate.

It is to be understood that the ceramic plate need not be alumina but can be barium titanate or of any metallic oxide or mixture of metallic oxides. The silver, prior to melting, need not be spherical but can be any shape which facilitates initial mounting in the orifices or which facilitates protrusion of the silver from the ceramic surface. Thus, it can be round, oblate, elongated, etc.

The use of silver for the interconnection masses herein is believed to result in a unique melt-bond between the silver and the curved wall in the ceramic plate. By melt-bond as employed herein, is meant that it is a bond created by subjecting the silver to a temperature substantially above its melting point so that on cooling, an interlinking or intermeshing-type union takes place between the silver and natural irregularities in the wall ofthe ceramic. The bond formed by this technique is so strong that normally the ceramic substrate breaks before a parting of the silver and ceramic can be effected on testing the bond. it is also to be understood that the term volume herein as applied to a trough in the edge of the ceramic plate refers to the volume which would be defined by the curved wall and a plane connecting the ends otthe curved wall.

it is to be understood that either side of the ceramic plate, having the melt-bonded silver masses of the present invention, can have components or circuits mounted thereon. The term component is intended to include conductive paths or wires. The basic structure defined herein can also be employed as an electrical interconnect device sandwiched between two other planar surfaces carrying electrical components, wires or networks.

Obviously, many modifications and variations of the present invention are ossible in the light of the above teachin s. It is therefore, to e understood that within the scope of t e appended claims the invention may be practiced otherwise than as specifically prescribed.

lclaim:

l. in combination'a ceramic plate having across its narrowest dimension at least one curved wall, a silver mass meltbonded to each of said at least one curved wall, the volume of said mass being such that it ranges from slightly less than to considerably more than that which would completely fill the volume defined by such curved wall and said mass having no open space therethrough, and one or more electrical components in electrical communication with one or more of said silver masses so as to accommodate electrical communication to said components from either the edge or the opposite surface of said ceramic plate.

2. The combination of claim 1 wherein said curved wall defines at least one aperture of generally circular cross section in said plate.

3. The combination of claim 1 wherein said curved wall defines at least one trough across an edge of said plate, the cross section of said trough being part of a circle.

4. The combination of claim 1 wherein said plate has therein at least one aperture of generally circular cross section and at least one trough across an edge thereof the cross section of said trough being part ofa circle.

5. The combination of claim 1 wherein an insulating layer covers at least part of the electrical component side of said plate including the electrical components, the exposed portion of said silver masses and all of the electrical communication region between said masses and said components; said silver mass extending above the planar surface of said plate a distance which permits lap-removal of some of said insulating material from one or more of said silver masses without uncovering said components.

6. The combination of claim 2 wherein a plurality of said apertures are spaced in a circular pattern in said plate; wherein each silver mass extends beyond said apertures slightly above the planar surface of said plate to form a circular pattern of raised silver contact areas; and a rotatable nonconducting rotor positioned adjacent said contact areas, said rotor having at least one conducting area, which can be brought into electrical contact with a silver contact area on rotation of said rotor. 

